gateway整合websocket踩坑

在gateway整合websocket时，总共遇到的问题有两个，一个是jar冲突，另外一个是网关设置跨域后websocket连接上马上断开

jar包冲突

jar包冲突主要是：org.apache.catalina.connector.ResponseFacade cannot be cast to reactor.netty.http.server.HttpServerResponse，提示get请求报错500

15:30:38.092 [http-nio-9999-exec-1] ERROR c.m.g.e.GlobalErrorWebExceptionHandler - [handle,38] - org.apache.catalina.connector.ResponseFacade cannot be cast to reactor.netty.http.server.HttpServerResponse
java.lang.ClassCastException: org.apache.catalina.connector.ResponseFacade cannot be cast to reactor.netty.http.server.HttpServerResponse
	at org.springframework.web.reactive.socket.server.upgrade.ReactorNettyRequestUpgradeStrategy.getNativeResponse(ReactorNettyRequestUpgradeStrategy.java:182)
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ HTTP GET "/sys/websocket/1" [ExceptionHandlingWebHandler]
Stack trace:
		at org.springframework.web.reactive.socket.server.upgrade.ReactorNettyRequestUpgradeStrategy.getNativeResponse(ReactorNettyRequestUpgradeStrategy.java:182)
		at org.springframework.web.reactive.socket.server.upgrade.ReactorNettyRequestUpgradeStrategy.upgrade(ReactorNettyRequestUpgradeStrategy.java:162)
		at org.springframework.web.reactive.socket.server.support.HandshakeWebSocketService.lambda$handleRequest$1(HandshakeWebSocketService.java:235)
		at reactor.core.publisher.FluxFlatMap.trySubscribeScalarMap(FluxFlatMap.java:151)
		at reactor.core.publisher.MonoFlatMap.subscribeOrReturn(MonoFlatMap.java:53)
		at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:57)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.Mono.subscribe(Mono.java:4252)
		at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
		at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
		at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at com.alibaba.csp.sentinel.adapter.reactor.MonoSentinelOperator.subscribe(MonoSentinelOperator.java:40)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)
		at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:64)
		at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:52)

我出现这种情况主要是调用feign接口，引用的包里面有如下冲突

<dependency>
	<groupId>javax.servlet</groupId>
	<artifactId>javax.servlet-api</artifactId>
</dependency>
 <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
 </dependency>
 <dependency>
	<groupId>javax.servlet</groupId>
	<artifactId>jstl</artifactId>
</dependency>
<dependency>
	<groupId>org.apache.tomcat.embed</groupId>
	<artifactId>tomcat-embed-jasper</artifactId>
</dependency>

解决办法:我是使用的idea，可以利用idea自带的jar包依赖来查看当前项目引用情况，具体ctrl+shift+alt+u来查看依赖情况，找到上面的jar包，去除依赖

连上websocket后立马断开问题

报错java.lang.UnsupportedOperationException，就是在请求头那块报错不支持

2022-08-26 16:12:11.334 ERROR 20032 --- [ctor-http-nio-2] o.s.w.s.adapter.HttpWebHandlerAdapter    : [7e7b8a68-1] Error [java.lang.UnsupportedOperationException] for HTTP GET "/plat/approveabc/websocket/1123213", but ServerHttpResponse already committed (200 OK)
2022-08-26 16:12:11.338 ERROR 20032 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [id: 0x7e7b8a68, L:/127.0.0.1:8081 - R:/127.0.0.1:56941] Error finishing response. Closing connection

java.lang.UnsupportedOperationException: null
	at org.springframework.http.ReadOnlyHttpHeaders.set(ReadOnlyHttpHeaders.java:106) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ org.springframework.web.cors.reactive.CorsWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ HTTP GET "/plat/approveabc/websocket/1123213" [ExceptionHandlingWebHandler]

查看代码，发现是gateway处理跨域时使用的

UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        final CorsConfiguration config = new CorsConfiguration();
        // 允许cookies跨域
        config.setAllowCredentials(true);
        // #允许向该服务器提交请求的URI，*表示全部允许，在SpringMVC中，如果设成*，会自动转成当前请求头中的Origin
        config.addAllowedOrigin("*");
        // #允许访问的头信息,*表示全部
        config.addAllowedHeader("*");

后来换成

  return (exchange, chain) -> {
            ServerHttpRequest request = exchange.getRequest();
            if (!CorsUtils.isCorsRequest(request)) {
                return chain.filter(exchange);
            }
            ServerHttpResponse response = exchange.getResponse();
            HttpHeaders headers = response.getHeaders();
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, "*");
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, "*");
            headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, "*");
            headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, "3628800");
            return chain.filter(exchange);
        };

就可以解决问题,后面那种解决跨域是reactive，在网关最好使用这种响应式编程，不然问题可能会很多